CA1278469C - Method of the secondary combustion promotion for a fluidized bed incinerator - Google Patents
Method of the secondary combustion promotion for a fluidized bed incineratorInfo
- Publication number
- CA1278469C CA1278469C CA000527709A CA527709A CA1278469C CA 1278469 C CA1278469 C CA 1278469C CA 000527709 A CA000527709 A CA 000527709A CA 527709 A CA527709 A CA 527709A CA 1278469 C CA1278469 C CA 1278469C
- Authority
- CA
- Canada
- Prior art keywords
- fluidized bed
- air
- secondary air
- refuse
- incinerator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/30—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having a fluidised bed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
- F23G5/027—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Incineration Of Waste (AREA)
- Fluidized-Bed Combustion And Resonant Combustion (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A secondary combustion method for combustible gases generated by thermal decomposition in burning refuse such munici-pal wastes in a fluidized bed incinerator in which the refuse is fluidized, together with a fluidizing medium such as sand, by the primary air, and burnt and decomposed. The pyrolysis gas is com-pletely burnt by the secondary air in a grid shape in multiple stages, which is formed inside the combustion chamber of the incinerator. The non-combustible gas and smut densities within exhaust gas are also reduced. Further, the combustion chamber temperature can be maintained at a high level by carrying out secondary combustion swiftly.
A secondary combustion method for combustible gases generated by thermal decomposition in burning refuse such munici-pal wastes in a fluidized bed incinerator in which the refuse is fluidized, together with a fluidizing medium such as sand, by the primary air, and burnt and decomposed. The pyrolysis gas is com-pletely burnt by the secondary air in a grid shape in multiple stages, which is formed inside the combustion chamber of the incinerator. The non-combustible gas and smut densities within exhaust gas are also reduced. Further, the combustion chamber temperature can be maintained at a high level by carrying out secondary combustion swiftly.
Description
~2~6~
This invention relates to a method of incinerating sub-stances such as municipal wastes and industrial wastes (called ~refuse~ hereinafter) while ~luidizing them in a fluidized bed.
More particularly, it relates to a method of the secondary com-bustion promotion for a fluidized bed incinerator for post-com-busting the combustible gas produced after pyrolysis in the upper part of the incinerator after burning and decomposing the refuse in the fluidized bed.
The fluidized bed incinerator is known for incinerating and disposing of such refuse as municipal wastes. The incinera-tion/disposition method of the refuse in thls fluidized bed incinerator is to burn the refuse while fluidizing it with air.
In order to improve the fluidization and combustion of the refuse, such types of fluidizing medium as sand is fed together with the refuse into the fluidized bed.
general type of fluidized bed incinerator is equipped ~ith a plurality of air diffuser tubes or air diffuser plates (called "air diffusers~ hereinafter) for blowing the air down to the lower section of the incinerator hody, and further, the upper ; section of the incinerator body is equipped with a refuse feeding unit and a fluidizing medium feeding unit. The refuse is burnt while both the refuse and the fluidizing medium thrown onto the air diffusers inside the incinerator body are fluidized by the primary air blown from the air diffusers. Th0 refuse generally contains a variety of materials such as low calorie refuse, e.g.
food discards, high calorie refuse, e.g. plastics and rubber, refuse of the type shredded or chipped furniture, or refuse of the type fragmented metallic or vitreous containers, bottles or cans. Of the reEuse, as it is fed to the fluidized bed, the com-bustibles are burnt, of which the plastics and similar substances are melted by heat to generate pyrolysis gases, and the incom-bustibles such as metal and glass are left unburnt (called "combustion residuel~ hereinafter). As the fluidizing medium is gradually fed onto the fluidized bed, a moving bed of fluidizing ~7~ 9 medium descends. Therefore, while the combustibles are burnt or decomposed within the fluidlzed bed, the combustlon residue passes down out of the incinerator together with the fluidizing medium through the gaps among the air diffuser tubes at the lower section of the fluidized bed. The fluidi~ing medium is separated ~rom combustion residue, and again fed to the fluidized bed.
Secondary air is supplied into the upper section of the fluidized bed, where the generated pyrolysis gases are burnt.
Because, in this fluidized bed incinerator, the sand thrown into the fluidized bed, which is the fluidizing medlum, is oscillated while descends and is heated, it promotes the agitation and dis-persion of the refuse. For this reason, the refuse thrown onto the fluidized bed is dispersed uniformly und0r the presence of fluidizing medium to be dried, ignited, decomposed, and burnt instantaneously. Further, the ash and dust produced therein are passed with the fl~idizing air, out of the upper section of the incinerator and collected by an electrostatlc precipitator.
Consequently, the refuse thrown onto the fluidized bed is disposed of almost completely, leaving behind some metallic, vitreous, or ceramic residue. ~ha amount of these substances in the refuse is usually 2%, and therefore fluidized bed incinerator can dispose of 98% of thP refuse.
The fluidized bed has the advantage that it can reduce the volume of combustion residue to 1/3 compared with a conven-tional mechanical incinerator such as a stoker-type incinerator.
However, the refuse thrown onto the fluidized bed is burnt and decomposed at high speed so that the refuse can't be stably combusted. The refuse has different calorific value depending on the type of refuse, and it is often difficult to always supply a constant volume onto the fluidized bed. When a large amount of the refuse is thrown all at once onto the fluidized bed, then a large quantity of pyrolysis gases and smuts ~ - 2 -. .
~27~3~69 are also generated simultaneously even though the refuse is burnt and decomposed instantaneously. In this instance, it is impossible not only to completely secondarily combust a large quantity of pyrolysis gases wlth the secondary air inside the incinerator but it is also'difficult to collect the large quantity of smuts contained ln the~exhaust gas by means of electrostatic precipitator entirely. i, . The present,invention provldes;a method for burning.and decomposing the refuse slowly inside thé'fluidized bed incinerator and in secondarily combusting the generated combustible gases in,-the upper section.,of the incinerator, for improving the combustion of the mixture''jof combustible gas and secondary air, and for maintàining the temperature of the combustible gas in the incinerator at a high lev,el.
, he present invent~on also shows the combustlon of 'refuse in the fluidized bed by in~ecting.:':the secondary air into the combustion chamber in order to carry out secondary combustion.
' ' ' ' ' "''~
, ., " According to the pre~ent invention there is provided a method of operating;a;fluidized.bed inclnerator which promotes ,, . ,secondary combustion`of combustlble gasés.generated in the 'Ij~,; fluidized,bed, comprising the steps o$~'.(a) forming a fluidized ,25 ,- bed in said incinerator by'fluidizing refuse and a fluldizing .. , medium with primary.air,'the primary,,air.',,being blown into the fluidized by air diffuser tubes providëdl 1D the lower part of the incinerator, the air;diffuser tubes,extending generally parallel ,.:. to each:'other; ~b) feediny the rè~se,and'the fluidizlng medium 3~: into sald fluidiæed,bed; (c) burning ànd'~thermally decomposing ',j; the.re~use inside the'fluidized bed; the,',burning and .., :' decomposition; of said,refuse re,sulting.i~,the generation of com-.,. b,ustible'gas inside saidlincinerator;~l(d) forming a downward flow': , of the combination of the combustion resjldue of said refuse and .
. 35 the fluidizing medium lnside the,fluidi~ed bed through the air _ ~ " " ',1". . . \
!~, ~'~71!3~L~5g diffuser tubes, and discharging said combination fxom the bottom of the incinera-tor; (e) separating the fluidizing medium from the combustion residue in a sieve, and then recirculating the separated fluidizing medium to the fluldized bed (f) supplying secondary air into a combustion chamber inside said inclnerator S for performing secondary combustion of sald combustible gas, the supplying of said secondary air being performed by blowlng said secondary air into said combustion chamber and horizontally across said combustion chamber through a plurality of groups of nozzles arranged in vertically staggered stages, the nozzles in 1~ each group being arranged in several horizon-tal rows, gro~ps of the nozzles belng alternately located in a pair of opposing side walls and Eorming parallel, staggered streams of air directed toward an opposite one of said side walls; and (g) generating a vortex of a mixture of the combustible gas and the secondary air in each space between two horizontal streams of the secondary air in each space between two horizontal streams of the secondary air supplied through two groups of nozzles provided in said opposing side walls.
Thus, the method of the present invention comprises such functions as fluidizing with the primary air the refuse such municipal wastes and the fluidizing medium which are supplied into the fluidized bed incinerator. In order to form the fluidized bed, the refuse and the fluidiziny medium are supplied to the fluidized bed, not only being burnt but also decomposed, and the secondary air blows into the combustion chamber at the upper section inside the incinerator for secondarily combustion of the combustible gases which are produced by the thermal decomposition of the refuse, and the secondary air being blown into the combustion chamber.is blown out from a group of nozzles.
which are installed in vertical multiple stages and paral:Lel each other in the horizontal direction at least to one side of the incinerator walls so that the secondary alr from each nozzle can flow horizontally across the combustion chamber.
. .. 1/, ~ ~
'~3 ~2~ S9 In one embodiment of the yresent invention the fluidizing medlum with combustion residue is taken out of a lower section oE the fluidlzed bed, and fed back to the fluidized bed after separated from the combustion residue. Suitably the fluidizing medium comprlses sand. Desirably the fluidized bed is formed by fluidizing the re~use and the fluidizing medium with the primary air blown from a plurality of nozzles provldad along either side of air diffuser tubes lald ln a grid shape at a lower section of incinerator body.
In another embodiment oE the present invention a plurality of the nozzle groups are provided ln multiple stages vertically and also in parallel in the horizontal direction, re-spectively on the opposite incinerator walls inside the combus-tion chamber. Suitably the secondary alr blown out of the nozzle group in the lowest ~tage is passed toward the flames from the refuse within the fluidized bed, and disperses the flames uniformly. Desirably the nozzle group in the lowest stage mounted - 4a -.~ , 78~
on the incinerator is such that a secondary air str~am is formed at 0.1 -to 1.5 m from the upper surface of the fluidized bed.
In a further embodiment of the present invention the adjacent nozzle interval in a horizontal direction is from 200 to 600 mm. Suitably each nozzle at each horizontal stage of the nozzle group is connected to a header to which the secondary air with a pressure higher than 250 mmAq is supplied to blow the secondary air out of each nozzle. Desirably the total air volume of the primary air and the secondary air is from 1.4 to 1.7 times of that of the theoretical air volume for refuse. More desirably primary and secondary air are approximately in the ratio of l:l.
The present invention will be furthe.r illustrated by way of the accompanying drawings, in which:-Fig. 1 is a schematic sectional view of a fluidized bedincinerator, according to one embodiment of this invention;
- 20 Fig. 2 is a sectional view on line II-II of Fig. l;
Fig. 3 is the graph showing the chronological change of CO gas and 2 gas densities within the exhaust gas in the method of this invention;
Fig. 4 is graph indicating the chronological change in the smuts in the method invention;
Fig. 5 is a graph showing the chronological change in Co gas and 2 gas densities in the exhaust gas in the case of a conventional combustion method; and Fig. 6 is a graph indicating the chronologlcal change of the smuts in a conventional method.
Hereinafter, the preferred embodiment example of the fi~
secondary combustion promotion method for the fluidized bed incinerator according to this invention will be described refer-ring to accompanying drawings.
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In Fiy. 1, the reference numeeal 10 is the incinerator body ~ormed of the refractory walls 12, which comprises the rectangular wall 14, side walls 10 and an inverted rectangular pyramid bottom wall 18 connected to the lower section of the said side walls 16. The side walls 16 comprise the upper wall 16a in which a combustion chamber 20 (free-board sect;on), described later, is formed, the wall 16b which is inclined inwardly from the said upper wall 16a and the vertical wall 16c extending vertically from the lower section of the said inclined wall 16b and connected with the bottom wall 18.
An exhaust port 19 is provided on the top wall 14, and a discharge port 22 is provided at the end of bottom wall 18.
In the space enclosed by the vertical wall 16c, a number of air diffuser tubes 24 are provided in parallel each other to blow the primary air Eorming the fluidized bed described later.
The air diffuser tubes 24 are extended through the vertical wall 16c, outside the incineratoe body 10, and are connected to the fluidizing air chargin~ tube 26.
On either the side of each air diffuser tube 24, the nozzle holes 25 are provided along the length direction at internals ~
~2~8~
The duct 30 through which such refuse 18 as municipal wastes is thrown onto the air diffuser tubes 24 is connected to the upper section wall 16a of the incinerator body 10, and the precipitator 31 is connected to the said duct 30.
The precipitator 31 compromises a casing 34 connected to the duct 30 and a screw 36. This casing 34 compromises a hopper section 38 for the refuse 28. The refuse 28 thrown into this hopper section 38 is transferred to the duct 30 by the rotation of screw 36 via the duct 30, and fed onto the air diffuser tubes 24.
On the upper section wall 16a of the incinerator body 10, a charging port 37 is provided to feed such fluidizing medium as sand into the incinerator body 10. This fluidizing medium 32 is fed onto the air diffuser tubes 24 through the charging port 37 from the circulation unit described later.
~ luidizing air charging tube 26, not shown in the figure, is connected to the air charging source for supplying the air to air diEfuser tubes 24, where the air comes out, as shown by the arrow in figure, from each nozzle 25 of the air diffuser tubes 24. The refuse 28 along with the fluidizing medium 32 which is fed onto the air diffuser tubes 24 is fluidized by the said air to Eorm the fluidized bed 40.
~`2t78~S9 ~ screw conveyor 46 is connected to the discharge port 22 of incinerator body 10 for transfer ~F the fluidizing medium 32 and the combustion residue of the refuse 28 to the separator 44 after these substances comes through the gaps among the air diffuser tubes 24.
A separator contains sieve 48 which separates the fluidizing medium 28 from the combustion residue 42. The combustion residue 42 remains on the sieve 48 and is discharged from a discharge port 45 of the separator 44. The fluidizing medium 28, after passing through the sieve 48, is fed back to the fluidized bed 40 via the charging port 37 through a circulation line 50 structured with the vertical conveyor, etc. which is connected to the separator 44.
To the upper section wall 16a making up the combustion chamber 20 of the incinerator body 10, a r~umber of nozzles 52 are installed in vertically arranged at multiple stages and in the horizontal direction, too.
The nozzles 52 are vertically provided in several stages in the incinerator body 10, for instance, installed in four stages as shown in the figure, where the lowest stage of nozzle group 52a and the 3rd stage nozzle group 52c are installed to the identical side face of incinerator body 1, wllile the 2nd stage nozzle group 52b and the 4th stage nozzle ~!L27~ 9 group 22d are provided on the wall face opposite the lowest stage nozzle group 52a and the 3rd stage nozzle group 52c.
These opposed nozzle group from 52a through 52d are installed in a manner so as to form the secondary air flow as shown by arrows 52A, 52B, 52C and 52D respectively toward the center 0 of the incinerator body 10 as shown in the figure.
Each noæzle group 52 shall be, as shown in Fig. 2, installed so that a In~rnbe~ of nozz].es may be mounted in parallel to the header 56 and each of these nozzles may pass through the upper wall 16b and face the interior of combustion chamber 20.
These nozzles 54 have an inside diameter of 40 to 80 mm or a square from 30 mm x 60 mm to 40 mm x 100 mm, and the horizontal interval "1" for nozzles is from 200 to 600 mm.
As shown in Fig. 1, not only the secondary air charging tube 58 but also the damper 60 are connected to the header tube 56 in each stage respectively. The secondary air supplied to the header 56 from the secondary air charging ;tube 58 is maintained at a pressure higher than 250 mmAq by the damper 60, and the secondary air from each nozzle of 54 is blown across the combustion chamber 20 like the two-dot chain line shown in the figure.
~78~.~g The lowest stage no~zle group 52a is mounted in such a position where the height "h" from the upper face of the fluidized bed 40 to the air flow 52 from those nozzles is 0.1 to 1.5m.
The primary air blown out of the air diffuser tubes 24 and the secondary air blown out of the nozzle groups 52a through d are adjusted with a ratio from 1:3 to 3:2, or preferably to the catio of 1:1, or further, the total air ratio is adjusted in the range from 1.4 to 1.7 against the theoretical air volume for c~mbust~on of the re~use, The method for burning the reEuse in the aforementioned fluidized bed incinerator will be described.
The refuse 28 is fed onto the air diffuser tubes 24 inside the incinerator body 10, Erom the precipitator 32 via the duct 30, and the fluidizing medium 32 is fed from the ~ circulation unit 50 via the c;larging port 37.
; On the other hand, the fluidizing air is fed to each air diffuser tubes 24 from the fluidizing air charging tube 26, and the primary air is blown out of nozzles 25 oE the said air diEfuser tubes 24, as shown by the arrow in the figure.
The refuse 28 and the fluidizing medium fed onto the air diEfuser tubes 24 are fluidized by the primary air blown out of the nozzles tubes 25.
~L2~7~ 6~
A plurality ~f s-tart-up burners are installed inside the incinerator body 10 ~not shown in the figure) and the refuse 28 inside the fluidised bed 40 is burnt by the flames feom burners when the operation is started.
Rfter the refuse 2~ inside the fluidized bed 40 is burnt with the Eluidizing air, the ignition by burners is ciesed.
The flame toward the fluidized bed 40 is emitted over the entire surface of the fluidized bed 40 by the air flow 52 blown out in a grid shape from the lowest stage nozzles group 52a, and the flame over the said fluidized bed 40 can't only be controlled but the pyrolysis gas generated by the thermal decomposition can also be dispersed uniformly.
The combustion heat of the refuse 28in fluidized becl40 causes some of the refuse 28 to be decomposed into the pyrolysis gas. This pyrolysis gas, containing such combustible gases as H2, CO and hydrocarbonaceous gases, is secondarily burnt by the secondary air blown in from the nozzles 54 in the combustion chamber 20 at the upper part inside the incinerator body 10.
The combustible gas produced, while ascending in the combustion chamber 20, is burnt completely by the secondary air 52B, 52C and 53D with a velocity higher than 50 m/sec which are blown in dnd formed in a grid shae from the ~27~ ii9 nozzle groups 52b, 52c and 52d at each stage. Since these secondary air 52B, 52C and 52D are formed into a grid shape in some stages vertical~y across the combustion chamber 20 as shown in Fig. 2 and the interior of the combustion chamber 20 is covered by the secondary air in the upper and lower stages, the combustible gas rising from the fluidized bed 40 is prevented from blowing through, and thus the combustible gas can be burnt positively, swiftly and stably in combustion chamber 20 entirely.
Further, the total air ratio required for combusting the refuse 28 in the conventional method is 1.7 to 2.0 against the theoratical air volume, which can be lowered to 1.4 to 1.7 by this invention, and the temperature inside the free-board section (combustion chamber) can also be maintained at a high level.
The exhaust gas which is generated with the combustion of the refuse 28 and the secondary combustion of pyrolysis gas is brought oUt~of the incinerator through the exhaust po~t 19. Containing a high calorific value, this exhaust gas is used as the heat source for heating the water for boilers, etc. No smuts are contained in the exhaust gas~ because dust is removed by an electric precipitator aEter it is used as the heat source.
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The refuse 28 and the fluidizing medium 32 are fed sequentially to the fluidized bed 40, and the refuse 28 is burnt and decomposed as mentioned earlier.
On the other hand, the fluidizaing medium 32 promotes the agitation and dispersion of thrown refuse 28, and also forms the moving bed which descends inside the fluidized bed 40. Thereafter, the fluidizing medium 32 flows down, with the combustion residue 42 among the refuse, through the gaps among the air diffuser tubes 24, and remains on the bottom wall 18, and forms the filling bed below the air diffuser tubes 24 with the fluidizing medium 32 and the combustion residue 42 contained therein. This filling bed regulates the level of the fluidized bed 40 which is formed over the air diffuser tubes 24. The filling bed increased by the increment of combustion residue is discharged by a screw conveyor which is installed in a lower position. The screw conveyor 46 transfers the fluidizing medium 32 and the combustion residue 42 to the separator 44.
In the separator 44, the combustion residue 42 is separated from the fluidizing medium 42 by the sieve 48, and the combustion residue 42 is discharged out of the discharge port 45 while the fluidizing medium 32 is fed again to the - fluidized bed 40 by the circulation line 50.
,~
~z~
Fig. 3 and Fig. 5 show the examples of chronological change of C0 gas density and 2 gas density when the refuse is burnt in the fluidized bed incinerators, according to the present invention and -the conventional way.
Municipal wastes are used as refuse in both cases of the presen-t invention and the conventional case , and fed 2.5 tons/h, while the method of blowing secondary air is different each o-ther. In the example in Fig. 3, in addition to the present invention, temperature of the fluidized bed is controlled at 600 c.
IN the conventional example, the C0 gas among pyrolysis gas , shose density is represented by "a" is periodically produced at a density higher than 5,000 ppm as shown in Fig. 5, and the oxygeri density "b" on that occasion also becomes lower than 5% . This means that the refuse is not stably burnt insied -the fluidized bed and that a large a~olln$
of pyrolysis gas represented by C0 gas is generated due to the changes in quality or volume of the refuse or tempera-ture or the fluidized bed, and i-t is Icnown that the supply of secondary air for combustion of these gases cannot follow the said changes of a subsequent so that oxygen densi-ty decreases, resulting an oxygen shortage.
~7~S91 In contrast, a favourable mixture of pyrolysis gas ris-ing out of -the fluidized bed with the secondary air is achieved in this invention, and sufficient secondary combustion in this invention, and sufficient secondary combustion is carried out in the free board section, so the combustion inside the incinerator can be completed and the C0 gas density "ao" can be suppressed to l,OoO ppm or below at minimum, shown in Fig. 3, and it is also known that the oxygen density ~bo~ can be reduced to around 10%, thus having the pyrolysis gas burnt stably.
Fig. 4 and Fig. 6 show th~ case of combining the means of fluidized bed temperature control with this invention and the chronological change of smut generated in a conventional example, respectively.
Smuts of smoke are measured by Lingelman smoke density indicator in both this invention and the conventional example, after the exhaust gas coming out of the fluidized bed incinerator is cooled down in the gas cooling unit and dust is removed by an electric precipitator.
AS indicated in Fig. 6, smoke with an indicated value higher than the critical point for vision ~0.5) is exhausted at lot in the conventional example. In the present invention, the smoke with a value higher than the critical point for vision ;(0.5) is exhausted only rarely as shown in Fig. 4.
~ - 16 -, ~27~;9 !
'shown in Fig. 4.
jIt will be appreciated that this inven-tion has the following excellent effects.
(1) As blowing the secondary air into the fluidized bed incinerator, the pyrolysis gas generated by thermal decomposition of the refuse can be secondarily burnt in a favorable manner by providing several stages of nozzle groups horizontally in the vertical direction of the free-board section and blowing the secondary air in a grid shape.
(2) The fluidized bed temperature can be controlled (mainly ; by being heated) with the secondary combustion flame by installing the lowest stage nozzle group to supply the air close to the upper surface of the fluidized bed.
This invention relates to a method of incinerating sub-stances such as municipal wastes and industrial wastes (called ~refuse~ hereinafter) while ~luidizing them in a fluidized bed.
More particularly, it relates to a method of the secondary com-bustion promotion for a fluidized bed incinerator for post-com-busting the combustible gas produced after pyrolysis in the upper part of the incinerator after burning and decomposing the refuse in the fluidized bed.
The fluidized bed incinerator is known for incinerating and disposing of such refuse as municipal wastes. The incinera-tion/disposition method of the refuse in thls fluidized bed incinerator is to burn the refuse while fluidizing it with air.
In order to improve the fluidization and combustion of the refuse, such types of fluidizing medium as sand is fed together with the refuse into the fluidized bed.
general type of fluidized bed incinerator is equipped ~ith a plurality of air diffuser tubes or air diffuser plates (called "air diffusers~ hereinafter) for blowing the air down to the lower section of the incinerator hody, and further, the upper ; section of the incinerator body is equipped with a refuse feeding unit and a fluidizing medium feeding unit. The refuse is burnt while both the refuse and the fluidizing medium thrown onto the air diffusers inside the incinerator body are fluidized by the primary air blown from the air diffusers. Th0 refuse generally contains a variety of materials such as low calorie refuse, e.g.
food discards, high calorie refuse, e.g. plastics and rubber, refuse of the type shredded or chipped furniture, or refuse of the type fragmented metallic or vitreous containers, bottles or cans. Of the reEuse, as it is fed to the fluidized bed, the com-bustibles are burnt, of which the plastics and similar substances are melted by heat to generate pyrolysis gases, and the incom-bustibles such as metal and glass are left unburnt (called "combustion residuel~ hereinafter). As the fluidizing medium is gradually fed onto the fluidized bed, a moving bed of fluidizing ~7~ 9 medium descends. Therefore, while the combustibles are burnt or decomposed within the fluidlzed bed, the combustlon residue passes down out of the incinerator together with the fluidizing medium through the gaps among the air diffuser tubes at the lower section of the fluidized bed. The fluidi~ing medium is separated ~rom combustion residue, and again fed to the fluidized bed.
Secondary air is supplied into the upper section of the fluidized bed, where the generated pyrolysis gases are burnt.
Because, in this fluidized bed incinerator, the sand thrown into the fluidized bed, which is the fluidizing medlum, is oscillated while descends and is heated, it promotes the agitation and dis-persion of the refuse. For this reason, the refuse thrown onto the fluidized bed is dispersed uniformly und0r the presence of fluidizing medium to be dried, ignited, decomposed, and burnt instantaneously. Further, the ash and dust produced therein are passed with the fl~idizing air, out of the upper section of the incinerator and collected by an electrostatlc precipitator.
Consequently, the refuse thrown onto the fluidized bed is disposed of almost completely, leaving behind some metallic, vitreous, or ceramic residue. ~ha amount of these substances in the refuse is usually 2%, and therefore fluidized bed incinerator can dispose of 98% of thP refuse.
The fluidized bed has the advantage that it can reduce the volume of combustion residue to 1/3 compared with a conven-tional mechanical incinerator such as a stoker-type incinerator.
However, the refuse thrown onto the fluidized bed is burnt and decomposed at high speed so that the refuse can't be stably combusted. The refuse has different calorific value depending on the type of refuse, and it is often difficult to always supply a constant volume onto the fluidized bed. When a large amount of the refuse is thrown all at once onto the fluidized bed, then a large quantity of pyrolysis gases and smuts ~ - 2 -. .
~27~3~69 are also generated simultaneously even though the refuse is burnt and decomposed instantaneously. In this instance, it is impossible not only to completely secondarily combust a large quantity of pyrolysis gases wlth the secondary air inside the incinerator but it is also'difficult to collect the large quantity of smuts contained ln the~exhaust gas by means of electrostatic precipitator entirely. i, . The present,invention provldes;a method for burning.and decomposing the refuse slowly inside thé'fluidized bed incinerator and in secondarily combusting the generated combustible gases in,-the upper section.,of the incinerator, for improving the combustion of the mixture''jof combustible gas and secondary air, and for maintàining the temperature of the combustible gas in the incinerator at a high lev,el.
, he present invent~on also shows the combustlon of 'refuse in the fluidized bed by in~ecting.:':the secondary air into the combustion chamber in order to carry out secondary combustion.
' ' ' ' ' "''~
, ., " According to the pre~ent invention there is provided a method of operating;a;fluidized.bed inclnerator which promotes ,, . ,secondary combustion`of combustlble gasés.generated in the 'Ij~,; fluidized,bed, comprising the steps o$~'.(a) forming a fluidized ,25 ,- bed in said incinerator by'fluidizing refuse and a fluldizing .. , medium with primary.air,'the primary,,air.',,being blown into the fluidized by air diffuser tubes providëdl 1D the lower part of the incinerator, the air;diffuser tubes,extending generally parallel ,.:. to each:'other; ~b) feediny the rè~se,and'the fluidizlng medium 3~: into sald fluidiæed,bed; (c) burning ànd'~thermally decomposing ',j; the.re~use inside the'fluidized bed; the,',burning and .., :' decomposition; of said,refuse re,sulting.i~,the generation of com-.,. b,ustible'gas inside saidlincinerator;~l(d) forming a downward flow': , of the combination of the combustion resjldue of said refuse and .
. 35 the fluidizing medium lnside the,fluidi~ed bed through the air _ ~ " " ',1". . . \
!~, ~'~71!3~L~5g diffuser tubes, and discharging said combination fxom the bottom of the incinera-tor; (e) separating the fluidizing medium from the combustion residue in a sieve, and then recirculating the separated fluidizing medium to the fluldized bed (f) supplying secondary air into a combustion chamber inside said inclnerator S for performing secondary combustion of sald combustible gas, the supplying of said secondary air being performed by blowlng said secondary air into said combustion chamber and horizontally across said combustion chamber through a plurality of groups of nozzles arranged in vertically staggered stages, the nozzles in 1~ each group being arranged in several horizon-tal rows, gro~ps of the nozzles belng alternately located in a pair of opposing side walls and Eorming parallel, staggered streams of air directed toward an opposite one of said side walls; and (g) generating a vortex of a mixture of the combustible gas and the secondary air in each space between two horizontal streams of the secondary air in each space between two horizontal streams of the secondary air supplied through two groups of nozzles provided in said opposing side walls.
Thus, the method of the present invention comprises such functions as fluidizing with the primary air the refuse such municipal wastes and the fluidizing medium which are supplied into the fluidized bed incinerator. In order to form the fluidized bed, the refuse and the fluidiziny medium are supplied to the fluidized bed, not only being burnt but also decomposed, and the secondary air blows into the combustion chamber at the upper section inside the incinerator for secondarily combustion of the combustible gases which are produced by the thermal decomposition of the refuse, and the secondary air being blown into the combustion chamber.is blown out from a group of nozzles.
which are installed in vertical multiple stages and paral:Lel each other in the horizontal direction at least to one side of the incinerator walls so that the secondary alr from each nozzle can flow horizontally across the combustion chamber.
. .. 1/, ~ ~
'~3 ~2~ S9 In one embodiment of the yresent invention the fluidizing medlum with combustion residue is taken out of a lower section oE the fluidlzed bed, and fed back to the fluidized bed after separated from the combustion residue. Suitably the fluidizing medium comprlses sand. Desirably the fluidized bed is formed by fluidizing the re~use and the fluidizing medium with the primary air blown from a plurality of nozzles provldad along either side of air diffuser tubes lald ln a grid shape at a lower section of incinerator body.
In another embodiment oE the present invention a plurality of the nozzle groups are provided ln multiple stages vertically and also in parallel in the horizontal direction, re-spectively on the opposite incinerator walls inside the combus-tion chamber. Suitably the secondary alr blown out of the nozzle group in the lowest ~tage is passed toward the flames from the refuse within the fluidized bed, and disperses the flames uniformly. Desirably the nozzle group in the lowest stage mounted - 4a -.~ , 78~
on the incinerator is such that a secondary air str~am is formed at 0.1 -to 1.5 m from the upper surface of the fluidized bed.
In a further embodiment of the present invention the adjacent nozzle interval in a horizontal direction is from 200 to 600 mm. Suitably each nozzle at each horizontal stage of the nozzle group is connected to a header to which the secondary air with a pressure higher than 250 mmAq is supplied to blow the secondary air out of each nozzle. Desirably the total air volume of the primary air and the secondary air is from 1.4 to 1.7 times of that of the theoretical air volume for refuse. More desirably primary and secondary air are approximately in the ratio of l:l.
The present invention will be furthe.r illustrated by way of the accompanying drawings, in which:-Fig. 1 is a schematic sectional view of a fluidized bedincinerator, according to one embodiment of this invention;
- 20 Fig. 2 is a sectional view on line II-II of Fig. l;
Fig. 3 is the graph showing the chronological change of CO gas and 2 gas densities within the exhaust gas in the method of this invention;
Fig. 4 is graph indicating the chronological change in the smuts in the method invention;
Fig. 5 is a graph showing the chronological change in Co gas and 2 gas densities in the exhaust gas in the case of a conventional combustion method; and Fig. 6 is a graph indicating the chronologlcal change of the smuts in a conventional method.
Hereinafter, the preferred embodiment example of the fi~
secondary combustion promotion method for the fluidized bed incinerator according to this invention will be described refer-ring to accompanying drawings.
. .
~ 27~
In Fiy. 1, the reference numeeal 10 is the incinerator body ~ormed of the refractory walls 12, which comprises the rectangular wall 14, side walls 10 and an inverted rectangular pyramid bottom wall 18 connected to the lower section of the said side walls 16. The side walls 16 comprise the upper wall 16a in which a combustion chamber 20 (free-board sect;on), described later, is formed, the wall 16b which is inclined inwardly from the said upper wall 16a and the vertical wall 16c extending vertically from the lower section of the said inclined wall 16b and connected with the bottom wall 18.
An exhaust port 19 is provided on the top wall 14, and a discharge port 22 is provided at the end of bottom wall 18.
In the space enclosed by the vertical wall 16c, a number of air diffuser tubes 24 are provided in parallel each other to blow the primary air Eorming the fluidized bed described later.
The air diffuser tubes 24 are extended through the vertical wall 16c, outside the incineratoe body 10, and are connected to the fluidizing air chargin~ tube 26.
On either the side of each air diffuser tube 24, the nozzle holes 25 are provided along the length direction at internals ~
~2~8~
The duct 30 through which such refuse 18 as municipal wastes is thrown onto the air diffuser tubes 24 is connected to the upper section wall 16a of the incinerator body 10, and the precipitator 31 is connected to the said duct 30.
The precipitator 31 compromises a casing 34 connected to the duct 30 and a screw 36. This casing 34 compromises a hopper section 38 for the refuse 28. The refuse 28 thrown into this hopper section 38 is transferred to the duct 30 by the rotation of screw 36 via the duct 30, and fed onto the air diffuser tubes 24.
On the upper section wall 16a of the incinerator body 10, a charging port 37 is provided to feed such fluidizing medium as sand into the incinerator body 10. This fluidizing medium 32 is fed onto the air diffuser tubes 24 through the charging port 37 from the circulation unit described later.
~ luidizing air charging tube 26, not shown in the figure, is connected to the air charging source for supplying the air to air diEfuser tubes 24, where the air comes out, as shown by the arrow in figure, from each nozzle 25 of the air diffuser tubes 24. The refuse 28 along with the fluidizing medium 32 which is fed onto the air diffuser tubes 24 is fluidized by the said air to Eorm the fluidized bed 40.
~`2t78~S9 ~ screw conveyor 46 is connected to the discharge port 22 of incinerator body 10 for transfer ~F the fluidizing medium 32 and the combustion residue of the refuse 28 to the separator 44 after these substances comes through the gaps among the air diffuser tubes 24.
A separator contains sieve 48 which separates the fluidizing medium 28 from the combustion residue 42. The combustion residue 42 remains on the sieve 48 and is discharged from a discharge port 45 of the separator 44. The fluidizing medium 28, after passing through the sieve 48, is fed back to the fluidized bed 40 via the charging port 37 through a circulation line 50 structured with the vertical conveyor, etc. which is connected to the separator 44.
To the upper section wall 16a making up the combustion chamber 20 of the incinerator body 10, a r~umber of nozzles 52 are installed in vertically arranged at multiple stages and in the horizontal direction, too.
The nozzles 52 are vertically provided in several stages in the incinerator body 10, for instance, installed in four stages as shown in the figure, where the lowest stage of nozzle group 52a and the 3rd stage nozzle group 52c are installed to the identical side face of incinerator body 1, wllile the 2nd stage nozzle group 52b and the 4th stage nozzle ~!L27~ 9 group 22d are provided on the wall face opposite the lowest stage nozzle group 52a and the 3rd stage nozzle group 52c.
These opposed nozzle group from 52a through 52d are installed in a manner so as to form the secondary air flow as shown by arrows 52A, 52B, 52C and 52D respectively toward the center 0 of the incinerator body 10 as shown in the figure.
Each noæzle group 52 shall be, as shown in Fig. 2, installed so that a In~rnbe~ of nozz].es may be mounted in parallel to the header 56 and each of these nozzles may pass through the upper wall 16b and face the interior of combustion chamber 20.
These nozzles 54 have an inside diameter of 40 to 80 mm or a square from 30 mm x 60 mm to 40 mm x 100 mm, and the horizontal interval "1" for nozzles is from 200 to 600 mm.
As shown in Fig. 1, not only the secondary air charging tube 58 but also the damper 60 are connected to the header tube 56 in each stage respectively. The secondary air supplied to the header 56 from the secondary air charging ;tube 58 is maintained at a pressure higher than 250 mmAq by the damper 60, and the secondary air from each nozzle of 54 is blown across the combustion chamber 20 like the two-dot chain line shown in the figure.
~78~.~g The lowest stage no~zle group 52a is mounted in such a position where the height "h" from the upper face of the fluidized bed 40 to the air flow 52 from those nozzles is 0.1 to 1.5m.
The primary air blown out of the air diffuser tubes 24 and the secondary air blown out of the nozzle groups 52a through d are adjusted with a ratio from 1:3 to 3:2, or preferably to the catio of 1:1, or further, the total air ratio is adjusted in the range from 1.4 to 1.7 against the theoretical air volume for c~mbust~on of the re~use, The method for burning the reEuse in the aforementioned fluidized bed incinerator will be described.
The refuse 28 is fed onto the air diffuser tubes 24 inside the incinerator body 10, Erom the precipitator 32 via the duct 30, and the fluidizing medium 32 is fed from the ~ circulation unit 50 via the c;larging port 37.
; On the other hand, the fluidizing air is fed to each air diffuser tubes 24 from the fluidizing air charging tube 26, and the primary air is blown out of nozzles 25 oE the said air diEfuser tubes 24, as shown by the arrow in the figure.
The refuse 28 and the fluidizing medium fed onto the air diEfuser tubes 24 are fluidized by the primary air blown out of the nozzles tubes 25.
~L2~7~ 6~
A plurality ~f s-tart-up burners are installed inside the incinerator body 10 ~not shown in the figure) and the refuse 28 inside the fluidised bed 40 is burnt by the flames feom burners when the operation is started.
Rfter the refuse 2~ inside the fluidized bed 40 is burnt with the Eluidizing air, the ignition by burners is ciesed.
The flame toward the fluidized bed 40 is emitted over the entire surface of the fluidized bed 40 by the air flow 52 blown out in a grid shape from the lowest stage nozzles group 52a, and the flame over the said fluidized bed 40 can't only be controlled but the pyrolysis gas generated by the thermal decomposition can also be dispersed uniformly.
The combustion heat of the refuse 28in fluidized becl40 causes some of the refuse 28 to be decomposed into the pyrolysis gas. This pyrolysis gas, containing such combustible gases as H2, CO and hydrocarbonaceous gases, is secondarily burnt by the secondary air blown in from the nozzles 54 in the combustion chamber 20 at the upper part inside the incinerator body 10.
The combustible gas produced, while ascending in the combustion chamber 20, is burnt completely by the secondary air 52B, 52C and 53D with a velocity higher than 50 m/sec which are blown in dnd formed in a grid shae from the ~27~ ii9 nozzle groups 52b, 52c and 52d at each stage. Since these secondary air 52B, 52C and 52D are formed into a grid shape in some stages vertical~y across the combustion chamber 20 as shown in Fig. 2 and the interior of the combustion chamber 20 is covered by the secondary air in the upper and lower stages, the combustible gas rising from the fluidized bed 40 is prevented from blowing through, and thus the combustible gas can be burnt positively, swiftly and stably in combustion chamber 20 entirely.
Further, the total air ratio required for combusting the refuse 28 in the conventional method is 1.7 to 2.0 against the theoratical air volume, which can be lowered to 1.4 to 1.7 by this invention, and the temperature inside the free-board section (combustion chamber) can also be maintained at a high level.
The exhaust gas which is generated with the combustion of the refuse 28 and the secondary combustion of pyrolysis gas is brought oUt~of the incinerator through the exhaust po~t 19. Containing a high calorific value, this exhaust gas is used as the heat source for heating the water for boilers, etc. No smuts are contained in the exhaust gas~ because dust is removed by an electric precipitator aEter it is used as the heat source.
- ~z~
The refuse 28 and the fluidizing medium 32 are fed sequentially to the fluidized bed 40, and the refuse 28 is burnt and decomposed as mentioned earlier.
On the other hand, the fluidizaing medium 32 promotes the agitation and dispersion of thrown refuse 28, and also forms the moving bed which descends inside the fluidized bed 40. Thereafter, the fluidizing medium 32 flows down, with the combustion residue 42 among the refuse, through the gaps among the air diffuser tubes 24, and remains on the bottom wall 18, and forms the filling bed below the air diffuser tubes 24 with the fluidizing medium 32 and the combustion residue 42 contained therein. This filling bed regulates the level of the fluidized bed 40 which is formed over the air diffuser tubes 24. The filling bed increased by the increment of combustion residue is discharged by a screw conveyor which is installed in a lower position. The screw conveyor 46 transfers the fluidizing medium 32 and the combustion residue 42 to the separator 44.
In the separator 44, the combustion residue 42 is separated from the fluidizing medium 42 by the sieve 48, and the combustion residue 42 is discharged out of the discharge port 45 while the fluidizing medium 32 is fed again to the - fluidized bed 40 by the circulation line 50.
,~
~z~
Fig. 3 and Fig. 5 show the examples of chronological change of C0 gas density and 2 gas density when the refuse is burnt in the fluidized bed incinerators, according to the present invention and -the conventional way.
Municipal wastes are used as refuse in both cases of the presen-t invention and the conventional case , and fed 2.5 tons/h, while the method of blowing secondary air is different each o-ther. In the example in Fig. 3, in addition to the present invention, temperature of the fluidized bed is controlled at 600 c.
IN the conventional example, the C0 gas among pyrolysis gas , shose density is represented by "a" is periodically produced at a density higher than 5,000 ppm as shown in Fig. 5, and the oxygeri density "b" on that occasion also becomes lower than 5% . This means that the refuse is not stably burnt insied -the fluidized bed and that a large a~olln$
of pyrolysis gas represented by C0 gas is generated due to the changes in quality or volume of the refuse or tempera-ture or the fluidized bed, and i-t is Icnown that the supply of secondary air for combustion of these gases cannot follow the said changes of a subsequent so that oxygen densi-ty decreases, resulting an oxygen shortage.
~7~S91 In contrast, a favourable mixture of pyrolysis gas ris-ing out of -the fluidized bed with the secondary air is achieved in this invention, and sufficient secondary combustion in this invention, and sufficient secondary combustion is carried out in the free board section, so the combustion inside the incinerator can be completed and the C0 gas density "ao" can be suppressed to l,OoO ppm or below at minimum, shown in Fig. 3, and it is also known that the oxygen density ~bo~ can be reduced to around 10%, thus having the pyrolysis gas burnt stably.
Fig. 4 and Fig. 6 show th~ case of combining the means of fluidized bed temperature control with this invention and the chronological change of smut generated in a conventional example, respectively.
Smuts of smoke are measured by Lingelman smoke density indicator in both this invention and the conventional example, after the exhaust gas coming out of the fluidized bed incinerator is cooled down in the gas cooling unit and dust is removed by an electric precipitator.
AS indicated in Fig. 6, smoke with an indicated value higher than the critical point for vision ~0.5) is exhausted at lot in the conventional example. In the present invention, the smoke with a value higher than the critical point for vision ;(0.5) is exhausted only rarely as shown in Fig. 4.
~ - 16 -, ~27~;9 !
'shown in Fig. 4.
jIt will be appreciated that this inven-tion has the following excellent effects.
(1) As blowing the secondary air into the fluidized bed incinerator, the pyrolysis gas generated by thermal decomposition of the refuse can be secondarily burnt in a favorable manner by providing several stages of nozzle groups horizontally in the vertical direction of the free-board section and blowing the secondary air in a grid shape.
(2) The fluidized bed temperature can be controlled (mainly ; by being heated) with the secondary combustion flame by installing the lowest stage nozzle group to supply the air close to the upper surface of the fluidized bed.
(3) Since the burning of pyrolysis gas in the lower section of the combustion chamber inside the incinerator can be done quickly, the combustible gas temperature within the combustion chamber can be maintained at a high level.
. ~.. . ~
. ~.. . ~
Claims (19)
1. A method of operating a fluidized bed incinerator which promotes secondary combustion of combustible gases generated in the fluidized bed, comprising the steps of: (a) forming a fluidized bed in said incinerator by fluidizing refuse and a fluidizing medium with primary air, the primary air being blown into the fluidized by air diffuser tubes provided in the lower part of the incinerator, the air diffuser tubes extending generally parallel to each other; (b) feeding the refuse and the fluidizing medium into said fluidized bed; (c) burning and thermally decomposing the refuse inside the fluidized bed, the burning and decomposition of said refuse resulting in the generation of combustible gas inside said incinerator; (d) forming a downward flow of the combination of the combustion residue of said refuse and the fluidizing medium inside the fluidized bed through the air diffuser tubes, and discharging said combination from the bottom of the incinerator; (e) separating the fludizing medium from the combustion residue in a sieve, and then recirculating the separated fluidizing medium to the fluidized bed; (f) supplying secondary air into a combustion chamber inside said incinerator for performing secondary combustion of said combustible gas, the supplying of said secondary air being performed by blowing said secondary air into said combustion chamber and horizontally across said combustion chamber through a plurality of groups of nozzles arranged in vertically staggered stages, the nozzles in each group being arranged in several horizontal rows, groups of the nozzles being alternately located in a pair of opposing side walls and forming parallel, staggered streams of air directed toward an opposite one of said side walls; and (g) generating a vortex of a mixture of the combustible gas and the secondary air in each space between two horizontal streams of the secondary air in each space between two horizontal streams of the secondary air supplied through two groups of nozzles provided in said opposing side walls.
2. The method of claim 1, wherein said fluidizing medium comprises sand.
3. The method of claim 1, wherein the secondary air blown into said combustion chamber through the group of nozzles in the lowest stage thereof is directed toward the flames from the refuse within the fluidized bed and disperses the flames uniformly, resulting in the production of another flame with resulting combustible gas and heating the fluidized bed with radiant heat generated thereby.
4. The method of claim 3, wherein at least a portion of the secondary air is supplied into said combustion chamber at a distance of between 0.1 and 1.5 meters from the upper surface of said fluidized bed.
5. The method of claim 1, wherein the secondary air is supplied into said combustion chamber by the nozzles in each group thereof at intervals of between 200 and 600 mm.
6. The method of claim 1, wherein the nozzles of each nozzle group are connected to a header, and the secondary air is supplied to said header at a pressure higher than 250 mm Hg in order to blow the secondary air out of each nozzle.
7. The method of claim 1, wherein the total air volume of the primary air and the secondary air is from 1.4 to 1.7 times of that of the theoretical volume of air required to combust the refuse.
8. The method of claim 7, wherein primary and secondary air are supplied approximately in the ratio of 1:1.
9. A method for combusting combustible gases in the combustion chamber of a fluidized bed incinerator of the type in which the burning and thermal decomposition of refuse introduced into a fluidized bed results in the generation of said combustible gas, and wherein the fluidized bed is formed by fluidizing said refuse and a fluidizing medium with primary air, comprising the steps of: (a) introducing pressurized secondary air into said combustion chamber so as to create a plurality of groups of vertically staggered horizontal streams of secondary air, said groups of horizontal streams being vertically spaced, half of said groups of horizontal streams of secondary air blowing from one side wall, the other half of the groups of horizontal streams blowing from the opposite side wall, two adjacent groups of said horizontal streams blowing in the opposite directions; and, (b) generating a vortex of a mixture of the combustible gas and the secondary air between said two adjacent air streams by supplying the secondary air so to horizontally flow in said opposite directions.
10. The method of claim 9, including the step of directing the air streams of the stage nearest said fluidized bed toward the flames emanating from said fluidized bed and in a manner to disperse said flames essentially uniformly.
11. The method of claim 9, wherein at least a portion of said secondary air is introduced into said combustion chamber at a point between approximately 0.1 and 1.5 meters above said fluidized bed.
12. The method of claim 9, wherein said parallel air streams are formed approximately between 200 and 800 mm from each other.
13. The method of claim 9, wherein the total volume of the primary and secondary air respectively supplied to said fluidized bed and said combustion chamber is from 1.4 to 0.7 times the theoretical volume of air required to combust said refuse.
14. The method of claim 9, wherein the primary air and the secondary air are respectively supplied to said fluidized bed and said combustion chamber in the ratio of approximately 1:1.
15. A fluidized bed incinerator having a fluidized bed for combusting refuse, comprising: an incinerator body; a plurality of parallel air diffuser tubes in a lower section of said body, each of said tubes having a plurality of openings on opposite sides thereof for supplying primary combustion air to said fluidized bed; means for supplying said primary combustion air to said tubes; means for introducing refuse onto said fluidized bed above said tubes, the thermal decomposition of said refuse in said fluidized bed resulting in the generation of pyrolysis gas; means below said tubes for removing combustion residue and a fluidizing medium from said lower section of said incinerator body;
means for separating said combustion residue from said fluidizing medium means for circulating the separated fluidizing medium back to said fluidized bed; and a plurality of groups of nozzles for supplying secondary air horizontally cross said incinerator body, said nozzles being vertically staggered and disposed in two opposing side walls in an upper section of said body, two adjacent streams of said secondary air having different vertically spaced paths, said nozzles in each group being arranged in a plurality of horizontal rows.
means for separating said combustion residue from said fluidizing medium means for circulating the separated fluidizing medium back to said fluidized bed; and a plurality of groups of nozzles for supplying secondary air horizontally cross said incinerator body, said nozzles being vertically staggered and disposed in two opposing side walls in an upper section of said body, two adjacent streams of said secondary air having different vertically spaced paths, said nozzles in each group being arranged in a plurality of horizontal rows.
16. The fluidized bed incinerator of claim 15, wherein said each group of nozzles is connected to a header attached to the outer surface of the side wall which the group of nozzles is located in, each nozzle penetrating the side wall and being directed toward the opposite side wall, said headers being provided with secondary air supply.
17. The fluidized bed incinerator of claim 16, wherein a damper means is provided between said secondary air supply and said headers in order to control the amount of secondary air to be supplied.
18. The fluidized bed incinerator of claim 17, wherein the pressure of the secondary air in said header is maintained higher than 250 mmHg.
19. The fluidized bed incinerator of claim 16, wherein the bottom group of said nozzles is located 0.1 to 1.5 meters above the uppermost surface of said fluidized bed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8946/1986 | 1986-01-21 | ||
| JP61008946A JPH0799253B2 (en) | 1986-01-21 | 1986-01-21 | Secondary combustion promotion method of fluidized bed furnace. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1278469C true CA1278469C (en) | 1991-01-02 |
Family
ID=11706835
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000527709A Expired - Fee Related CA1278469C (en) | 1986-01-21 | 1987-01-20 | Method of the secondary combustion promotion for a fluidized bed incinerator |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4744312A (en) |
| EP (1) | EP0237720B1 (en) |
| JP (1) | JPH0799253B2 (en) |
| CA (1) | CA1278469C (en) |
| DE (1) | DE3760976D1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3716088A1 (en) * | 1987-04-09 | 1989-02-02 | Muellverbrennungsanlage Wupper | METHOD FOR BURNING IN PARTICULAR MUELL |
| DE3737028A1 (en) * | 1987-10-31 | 1989-05-11 | Hoelter Heinz | METHOD FOR REDUCING CO IN COMBUSTION PLANTS, ESPECIALLY IN Fluid Bed Combustion Plants |
| JP2637449B2 (en) * | 1988-01-12 | 1997-08-06 | 三菱重工業株式会社 | Fluidized bed combustion method |
| CA1308964C (en) * | 1988-04-15 | 1992-10-20 | Brian Robin Blackwell | Method and apparatus for improving fluid flow and gas mixing in boilers |
| US4917026A (en) * | 1989-03-28 | 1990-04-17 | Macmillan Bloedal Limited | Debris burner |
| US5305698A (en) * | 1989-04-04 | 1994-04-26 | Blackwell Brian R | Method and apparatus for improving fluid flow and gas mixing in boilers |
| US5020451A (en) * | 1989-10-05 | 1991-06-04 | Ishikawajima-Harima Heavy Industries Co., Ltd. | Fluidized-bed combustion furnace |
| US5105748A (en) * | 1990-02-22 | 1992-04-21 | Mitsui Engineering & Shipbuilding Co., Ltd. | Fluidized bed combustion method for burning wastes |
| US5394937A (en) * | 1993-03-05 | 1995-03-07 | Nieh; Sen | Vortex heat exchange method and device |
| US5392736A (en) * | 1993-12-27 | 1995-02-28 | Foster Wheeler Energy Corporation | Fludized bed combustion system and process for operating same |
| US5941184A (en) * | 1997-12-02 | 1999-08-24 | Eco Waste Solutions Inc. | Controlled thermal oxidation process for organic wastes |
| US6418866B1 (en) * | 1998-06-16 | 2002-07-16 | Mitsubishi Heavy Industries, Ltd. | Operating method of fluidized-bed incinerator and the incinerator |
| CN113491883B (en) * | 2021-08-12 | 2022-06-28 | 江西全兴化工填料有限公司 | Metal packed fractionating tower for separating combustible gas |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3397657A (en) * | 1965-11-01 | 1968-08-20 | Tada Mitsuru | Apparatus for continuously burning wastes |
| CH577144A5 (en) * | 1974-10-03 | 1976-06-30 | Mustad Stoperi & Mek Verksted | Low grade fuel burning fluidised bed - uses fluidisation gas mixture made from primary air and combustion gases |
| US4060041A (en) * | 1975-06-30 | 1977-11-29 | Energy Products Of Idaho | Low pollution incineration of solid waste |
| GB1561237A (en) * | 1976-09-22 | 1980-02-13 | Ahlstroem Oy | Method of treating materials in a fluidized bed reactor |
| DK310979A (en) * | 1978-08-04 | 1980-02-05 | Energy Equip | PROCEDURE FOR CONTROLING THE OPERATION OF A FLUIDIZED BOTTLE LIFTING PLANT AND USING MEASURES IN THE IMPLEMENTATION OF THE PROCEDURE |
| JPS5524005A (en) * | 1978-08-07 | 1980-02-20 | Morimasa Maeshiro | Dust collecting brush for cleaning |
| JPS5693635U (en) * | 1979-12-21 | 1981-07-25 | ||
| DE3003245A1 (en) * | 1980-01-30 | 1981-11-12 | Deutsche Babcock Ag, 4200 Oberhausen | METHOD AND DEVICE FOR BURNING SUBSTANCES WITH HEAVY BURNING INGREDIENTS |
| JPS5830487A (en) * | 1981-08-19 | 1983-02-22 | Matsushita Refrig Co | Electromagnetic vibration compressor |
| US4548138A (en) * | 1981-12-17 | 1985-10-22 | York-Shipley, Inc. | Fast fluidized bed reactor and method of operating the reactor |
-
1986
- 1986-01-21 JP JP61008946A patent/JPH0799253B2/en not_active Expired - Lifetime
-
1987
- 1987-01-20 EP EP87100739A patent/EP0237720B1/en not_active Expired
- 1987-01-20 US US07/005,176 patent/US4744312A/en not_active Expired - Fee Related
- 1987-01-20 CA CA000527709A patent/CA1278469C/en not_active Expired - Fee Related
- 1987-01-20 DE DE8787100739T patent/DE3760976D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0237720B1 (en) | 1989-11-08 |
| JPS62169916A (en) | 1987-07-27 |
| EP0237720A1 (en) | 1987-09-23 |
| US4744312A (en) | 1988-05-17 |
| DE3760976D1 (en) | 1989-12-14 |
| JPH0799253B2 (en) | 1995-10-25 |
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